In the service of Esvele Graycastle's scheme, Despayr sought to dominate much of the Vast Swamp. Their goal was to tear a hole in the Weave of magic and so form a dead-magic zone over all the Vast Swamp. It was to be a powerbase for the followers of Shar.[3] In the Year of Lightning Storms, 1374 DR, at Despayr's behest, the Shadowscales made savage war upon the tribes of the Vast Swamp, particularly the other lizardfolk, who could hardly resist the shadowslain raiders. Many were slain and more were captured and carried off to the Lost Refuge, eventually returning as Shadowscales themselves to attack their own kin.[1]

In response, the Sharptooth, Blackscale, and Poison Dusk lizardfolk tribes formed an alliance under Kessessek. In early Eleint, Kessessek led a war party of Sharptooths, Blackscales, and Poison Dusks into Shadowscale territory around the Skull Staff. They hoped to slay some Shadowscales or their Shar-worshiping allies, or else capture some of the "dream walkers"—mind-controlled petitioners of a false Temple of Mystra—that regularly passed that way to the Lost Refuge. Kessessek and his kin recognized that these dream walkers were innocents and hoped to capture them, free their minds, and deny this resource to their shared enemy. In fact, they found adventurers in service to Mystra investigating the false temple and Sharrans' activities. Parlaying at the Sharptooth encampment, Kessessek aided and enlisted the adventurers to deal with the Shadowscales at the Lost Refuge.[1] There, seven Shadowscales and an allied grell attacked the camp, seeking to kill Kessessek, but the adventurers prevailed.[1][2] The adventurers later assaulted the Lost Refuge and defeated the Shadowscales there, including Ketsarra.[4]

As they journeyed through the Shadow Swamp, the adventurers likely discovered the Shadowscale Warren and fought the main bulk of the tribe there. Warchief Kossaandar is presumed to have been destroyed in the fighting, after which any remaining Shadowscales scattered across the Shadow Swamp, no longer answering Despayr, and a tribe no more.[5]

A Shadowscale was created when a captured lizardfolk was exposed to the necromantic magic of the shadow shard and transformed into an undead shadowslain creature.[6] Over time, all the original living lizardfolk of the tribe became shadowslain beings.[5] Their numbers included regular lizardfolk, Poison Dusks,[4] and Blackscales.[5][7]

The Shadowscales were always of evil bent, but other orientations they'd possessed in life remained unchanged. Although shadowslain were not bound to serve the owner of the shadow shard, the Shadowscales did so anyway.[6]

The Shadowscales maintained the same habits they'd had as living lizardfolk, even if no longer necessary, but over time they abandoned these. For example, the Shadowscales would retire to their lairs to mimic eating and sleeping, though they had no need to. They kept tools for hunting and trapping, but gave up using them, and not feeling the cold or needing light to see, they no longer bothered to light fires. Most tragically were the disused egg chambers, where no more eggs were laid and no young hatched.[8][5]

While some still lived, the Shadowscales believed in having the spirits of deceased kin watch over their unhatched eggs, and so placed their dried skulls in their egg chambers. The tribe had had a shaman, who'd been killed rather than transformed into a shadowslain.[5]

Appearing as a regular lizardfolk of its kind, a Shadowscale was swathed in flickering, rippling shadows, and its eyes glowed with a light described as unholy and hate-filled.[1][2] Otherwise, they looked much as they did in life, but as undead beings they became increasingly emaciated and decayed to the point of being skeletal.[9][note 1]

As a shadowslain, a Shadowscale carried a potent aura that could drain Weave magic from an arcane spellcaster who stood too close for too long. As a spell was lost, the Shadowscale was healed of any damage, according to the power of the spell.[6]

The semisolid shadowstuff that cloaked a Shadowscale served as a form of armor, helping to turn aside attacks. By bringing shadows with them, it also gave them great ability to hide.[6]

Otherwise, a Shadowscale had greater strength than a normal lizardfolk, the ability to see in darkness as with both low-light vision and darkvision, and all the benefits and drawbacks of being an undead monster. Being creatures of shadow, they were dazzled in the bright light day.[6]

Typical Shadowscales carried javelins or shortbows, but otherwise wore no armor and fought with their claws.[2] The veteran Shadowscale marauders wielded greatclubs and javelins, and the highest-ranked wore chain shirts.[7] They also sometimes used living grenades in defense of their warren: stirges or small vipers trapped inside sealed clay pots, which they would hurl at their foes. The hungry and angry creature would then attack the nearest living being, ignoring the undead Shadowscales.[10]

The Shadowscales placed captured stirges or small vipers inside sealed clay pots, which they would then hurl as grenades at their foes. Angry and hungry, the stirge or viper would then attack the nearest living being, ignoring the undead Shadowscales.[10]

The Shadowscales established their territory in the western Vast Swamp, around locations necessary to Sharran operations, including the Skull Staff[1] and the Lost Refuge, where they served as guards.[4] However, their main territory was in the Shadow Swamp, on the Plane of Shadow, where they had a number of settlements and outposts, the largest and most important of which was the mound-fort known as the Shadowscale Warren.[2] They also served as guards at the Shadow Citadel.[7]